• The sodium lauryl (dodecyl) sulfate polyacrylamide gel electrophoresis (SLS PAGE) patterns of keratin polypeptides were followed in 29 patients with psoriasis who were treated with middle wavelength ultraviolet (UV) radiation (UV B), oral methoxsalen, and long wavelength UV radiation (PUVA), or systemic antipsoriatic therapy. The keratin patterns from the Malpighian layer reverted to normal in several weeks, while those of the stratum corneum keratin reverted more slowly, often after clinical clearance of the lesions. These data may indicate that therapy should not be discontinued until there is production of normal stratum corneum polypeptides.